Experience suggests that they’d just move to a different URL if that happened. We’ve seen the “favourite URLs” thing before, on old forum posts, old help site posts, OSM data and more. Spam user profiles are probably the most popular, though.
Querying OSM data is possible by taginfo, and most of the others are searchable in some way; as noted above please email the DWG with any new examples to search for, but things like user profiles need hiding by the admins so just reporting those is the way to go (I did that last night with one new spammer of the litter bin above).